Airplane



Nov. 25, 1941. c 'r. BATTSI AIRPLANE 5 Sheets-Sheet 1 Filed April '7, 1959 Nov. 25, 1941.

C. T. BATTS AIRPLANE Filed April 7, 1959 5 Sheets-Sheet 2 0. T. BAT'rs Nov. 25, 1941,

AIRPLANE Filed April '7, 1939 5 Sheets-Sheet 3 c. T. BATTs Nov. 25, 1941.,

AIRPLANE Filed April v, 1959' '5 Sheets-Sheet 4 C. T. BATTS Nov. 25; 1941.

Filed April 7, 1939 5 Sheets-Sheet 5 Patented Nov. 25, 1941 ,UNITED srrss PATENT orica AIRPLANE Carl T. Batts, Pasadena, Calif.

Application April 7, 1939, Serial No. 266,612

35 Claims.

.This invention relates to certain improvements in airplanes, and the nature and. objects of the invention will be readily recognized and understood by those skilled in the aeronautical and related arts, in the light of the following explanation and detailed description of the accompanying drawings, illustrating what I now believe to be the preferred embodiments or aerodynamical and mechanical expressions of my invention, from among various other embodiments, arrangements, combinations and constructions, of which the invention is capable within the broad spirit and scope thereof.

With the standard systems of lateral or roll control employing the conventional types of ailerons forming trailing portions of opposite Wings, respectively, of an airplane, in which systems the ailerons are interconnected, and simultaneously differentially deflected vertically, in opposite directions, for lateral control, it is not practically possible to use full span wing flaps of the trailing under surface types, due primarily, to the fact that with such full span flaps in their normal raised, inactive positions, the necessary downward deflection of an aileron in the control operation of the conventional differentially actuated type of aileron control system is prevented. A type of lateral or roll control surface or aileron that will permit the use of a full span wing flap is exemplified by the so-called up-only aileron. Such type'of aileron forms a part of the trailing upper surface only of a wing and is-mounted for upward deflection only from neutral position to control positions and may, therefore, be positioned above a full span wing flap that forms a portion of the under surface only of the wing below such an upper surface aileron.

With such up-only ailerons mounted on opposite wings of an airplane, anaileron actuating or controlling system is provided, of a design and arrangement such that upon upward deflection of the aileron on one wing,'the opposite wing aileron is maintained inactive and at rest in its normal neutral position against deflection, and the rolling moment for lateral control is obtained primarily as a result of the upwardly defiected aileron. Ailerons of the up-only type provide an effective lateral or roll control means for an airplane and have the advantage of permitting the use of full span wing flaps to thereby gain the increased flap performance possible with full span flaps, as against the performance of the partial span flap necessitated by the conventional type of aileron system. However, ex-

perimental use of various designs of the up-only aileron has indicated that the up-only type of aileron possesses certain inherent disadvantages which, until eliminated or overcome, render such type of aileron unsatisfactory and impractical for use.

One of the most serious disadvantages thus indicated is that the operation of an up-only aileron, acting alone and designed to effectively replace two differentially acting ailerons, involves a substantial increase in control forces or aileron hinge moments. A brief comparison of the two systems should serve to show how this is brought about.

First, it should be recognized'that under normal conditions the air flow rearward along the under surface of a wing ismore effective as'an agent'acting upon a downwardly-deflected aileron than is the air flow rearward over the upper surface of a wing as an agent acting upon an upwardly-deflected aileron. Largely for this reason it is customary to work out the aileron linkage in such a way that the up-acting aileron of a differentially operated aileron system swings upward for full control through a relatively large angular deflection of 25 degrees perhaps, while the opposite and down-acting aileron swings downward through only 15 degrees. It is reasonable to conclude, therefore, that an aileron of the up-only type, acting singly to replace the two ailerons of the differentially operated system, and acted upon solely by the air flow above the upper surface of the wing, will need tobe deflected through at least as many degrees as would the up-acting aileron of the differentially operated system; and experimental data to date, covering various types of up-only ailerons other than that of my design, indicate that such uponly ailerons probably would need to be given a much greater angular displacement in order to prove suitably effective. An increase in angular displacement is certain to be attended by an increase in control forces.

Second, an up-only aileron, acting singly to replace the two ailerons of'a differentially operated system, must have approximately the same effective surface area as that of the two ailerons it replaces. 'And, due to the character of the air flow above the upper surface of the wing, it is at least possible that an increase in effective surface area will be demanded. Increase in surface area indicates an increase in control forces.

Third, the ailerons of differentially operated aileron control systems in common use today are aerodynamically balanced; and the aerodynamic balance is most effective as a means of reducing control forces. The up-only ailerons heretofore experimentally tested have not been designed to make an aerodynamic balance, if any, fully operative throughout the operating control range of the aileronespecia1ly with an under-surface flap in its neutral, retracted position, which is the natural position for such a flap under normal flight conditions.

In comparison with the control forces experienced in the operation of a differentially operated aileron control system, it is to be expect ed that an up-only aileron, of large surface area,

and perhaps deflected to high-angle positions for full control, must involve a substantial in.- crease in control forces when operated without an effective aerodynamic balance. 7 r V 7 My present invention is directed toward the reduction of the excessive control forces that must be overcome in the operation of an up-only aileron while maintaining effective lateral or roll control from such aileron; and, in accordance with the principles of my invention, I reduce the control forces encountered in the operation of the up-only aileron to its upwardly deflected control positions, by aerodynamically balancing such type of aileron in such a manner as to develop forces acting about the aileron axis of deflection in a direction to materially aid in the upward deflection of the aileron so as to thereby reduce the operating forces required to upwardly deflect the aileron to its control position.

The feature of the invention that provides for aerodynamic balancing of an up-only aileron is carried out by mounting the aileron for vertical rotation and angular deflection relative to the wing, about a balance hinge axis, located intermediate the leading andtrailing edges of the aileron to thereby form the portion of the aileron that extends forwardly of said axis, as an aerodynamic balance, to be reacted upon by the flow of air rearwardly over the upper surface of the wing to develop forcesactingabout the balance axis in a direction to aid upward deflection of the aileron. With the up-only aileron positioned as a portion of the trailing upper surface of a wing, with a portionof the wing structure, such as a wing flap, there beneath, if the aileron is rotated about its balance axis to upwardly deflect the trailing portion thereof, then the leading portion-or aerodynamic balance is deflected downwardly into a position in which the leading edge portion thereof, at least, will be blanketed from the air flow and the effectiveness of the balance and the balancing forces developed thereby, materially reduced, particularly throughout the range of maximum deflection of the aileron.

In order to make the balance portion of the aileron fully effective to obtain a maximum balancing force therefrom, my invention provides, as a further feature and characteristic thereof, the mounting of the aileron for bodily movement upwardlyabouta hinge axis spaced forwardly of and remote from the aileron so that in the control operation of the aileron it is initially moved from neutral position to a raised position fully exposed in and to the air flow over theupper surface of a wing and angularly deflected relative to the wing. The upwardly raised position of the aileron, relative to structure of the wing, is then such that the aileron may be upwardly deflected about the balance axis to its maximum control position with the balance portion of the aileron forward of the balance axis exposed to and acted upon by the rearward air flow over the wing throughout the range of upward deflection, with the development of increasing balancing forces as the angle of upward deflection of the aileron is increased. Thus, an up-only aileron in accordance with my invention, may be mounted to have movement for progressive angular displacement from neutral position to maximum upwardly deflected control position about two separate axes, which movement consists initially in bodily raising the aileron about a forward remote hinge axis to a position raised into the air flow over the wing, and then rotating the aileron about a balance axis intermediate the leading and trailing edges of the aileron when the latter is in this raised position to upwardly deflected control positions. The rotation and upward deflection of theaileron about its balance axis may be initiated after the aileron has reached maximum raised position about the remote hinge axis, or may be initiated prior thereto and during upward movement of the aileron about such hinge axis.

In the conventional aileron control system, where the opposite ailerons are interconnected and simultaneously vertically deflected in opposite directions, the hinge moments of these opposite ailerons are always balanced, and, therefore, with the ailerons in neutral position, the hinge moments of the individual ailerons are of no consequence, as there is a condition of static balance and the system may be actuatedthrough neutral with a smooth, uninterrupted movement of the control system, and without any abnormal or unusual feel being experienced by the pilot during such operation. However, in a lateral or roll control system of the up-only aileron type, there is an inherent condition of static unbalance encountered. This condition of static unbalance is caused by the fact that with the up-only aileron system, only one aileron of the opposite ailerons is upwardly deflected and in motion at any given time, so that, for example, the operation of such a system. to. lower an upwardly deflected aileron to neutral position, and then raise the opposite aileron from its at-rest, neutral position, it is necessary to first lower the upwardly deflected aileron into its at-rest position, and then topick up the opposite aileron from its position at rest in neutral for upward deflection thereof. The inertia loads set up by stopping one aileron and then picking up and setting the opposite aileron in motion from its at-rest position, are transmitted into the system and produce an abnormal, disturbing and unsatisfactory feel to the pilot in operating the system back and. forth through neutral position. In actual flight operation and use of the up-only type of aileron system, this abnormal feel in the control, due to static unbalance, is sufiiciently objectionable and disconcerting to the pilot as to bring this type of lateral or roll control system into disfavor and tend to prevent its practical adoption, notwithstanding certain definite advantages of the type such as referred to hereinbefore.

My present invention provides for the elimination or substantial reduction of this condition of static unbalance in an up-only aileron control system, so that in the operation of such type of system, the abnormal and objectionable feel encountered in the operation of the controls is done away with and a normal smooth operation of the control system is obtained throughout its operating range, including the neutral control positions. This condition of static unbalance, following the principles of my invention, is substantially eliminated by the application to each aileron of a force acting in a direction to raise the aileron from its neutral, at-rest, position, and of such a magnitude relative to the other forces acting in the control system, that as the system is operated through neutral to pick up and upwardly deflect the at-rest aileron, this raising force acts ahead of the raising force applied to the aileron by the system. Therefore, as the control system passes through neutral and movement thereof is continued to upwardly deflect the at-rest aileron, such aileron has already, in effect, been picked up and is being raised by said force so that the control system is relieved of the inertia load of picking up an at-rest aileron and a continuous smooth operation of the control system results with no abnormal or unbalanced loads imposed on the system to develop disturbing and unsatisfactory control system operating feel. Such applied force acts to, in effect, establish conditions in the system corresponding or equivalent to static balance, so that compensation of the conditions inherent in the up-only aileron type of control system, causing static unbalance, is obtained, and the abnormal and unsatisfactory feel to the pilot as the system is operated through the neutral position caused by static unbalance, is eliminated.

One of the primary requisites for lateral or roll control systems is that there be no appreciable lag between the start of the control surface movement, and the start of the resulting rolling motion, and that there should be no appreciable lag or time lapse between the movement of the pilots control and the start of the control surface movement. Another requisite is that the operation of the control system by the pilot for a control operation should be carried out as a single smooth and continuous movement from the start of the control operation to the conclusion thereof, and preferably that the control forces on the system should progressively increase as an aileron is displaced to maximum control position. With the up-only aileron of the type and design of, and mounted in accordance with, my present invention, for movement about separate hinge and balance axes, respectively, spaced a considerable distance apart, it is essential that the aileron actuating or controlling means to be operated by the pilot, must be arranged and designed to provide for a single continuous movement by the pilot in making any control operation. Further, the relationship between such actuating means and an aileron must be such that the raising of the aileron about its remote hinge axis, followed by the rotation of the aileron as it is in its raised position about its balance axis, should be carried out by a single smooth continuous movement of the control system on the part of the pilot, with a minimum of lag between the initiation of the control movement by the pilot and the rolling response from the aileron. In addition to the foregoing requisites, the con trol operating or actuating means for the up-only type of aileron must be such as will provide for the maintenance and positive holding of one aileron in its normal neutral, at-rest position against deflection throughout the vertical deflection of the opposite aileron, between its neutral at-rest position and its upwardly deflected control position.

Another object and a feature of this invention is the provision of a design and arrangement of a practical and relatively mechanic-ally simple.

design and arrangement of actuating or controlling means for up-only ailerons of the design and mounted as hereinbefore generally referred to, by which an aileron can be moved about its remote hinge axis and its balance axis in Vertically deflecting the aileron between its normal at-rest neutral position and its maximum upwardlydeflected control position, with a continuous, smooth and uninterrupted movement of the pilot control member for operating such means; and further, to provide such means by which the aileron opposite the aileron being deflected is positively held and maintained at rest against deflection from its normal neutral, at-rest position, during and throughout deflection of the opposite aileron by the operation of the actuating means.

A feature of one form of that mechanism of the controlling means that may be employed in carrying out the invention and through the medium of which the up-only aileron is progressively angularly displaced upwardly fromits neutral position about the separate remote hinge and balance axes, respectively, resides in an arrangement of a toggle type of linkage for raising the aileron about the remote hinge axis, in combination and cooperative relation with, a form of parallel linkage for rotating the aileron about its balance axis to upwardly-deflected control positions after the aileron has been raised or partially raised by the toggle linkage, with such toggle linkage so relatively arranged and associated with the parallel linkage that the toggle linkage functions to prevent transmission to the system of the major portion of the control forces developed by upward deflection of the aileron about its balance axis through the operation of the parallel linkage, particularly in the range of high angles of aileron upward deflection.

A control system of the invention in one possible form thereof, is further characterized by an arrangement of actuating mechanism that includes reciprocal linkages operatively coupled with the mechanisms for upwardly deflecting the ailerons to control positions and lowering the same from such positions, by which reciprocal linkages the aileron actuating mechanisms are alternatively operated so that upon actuation of the system to upwardly deflect one aileron, the opposite aileron actuating mechanisms are maintained inactive with such opposite aileron held in its neutral position against upward deflection therefrom; the combination and cooperative association of the pilot operated reciprocal linkage and the opposite aileron actuating mechanisms being such that an aileron may be actuated to and from control positions by continuous smooth and uninterrupted actuation of the pilot-operated control member, throughout the operating range of the system.

This invention includes, as a further novel feature thereof, the provision of trimming tabs to the ailerons of a lateral or roll control system of the up-only aileron type; and the arrangement flected to depress a wing without deflecting the aileron on which mounted from its neutral atrest position. The mounting of the trimming tabs-on the ailerons of the up-only type is further featured by the provision of independent adjusting mechanisms for such tabs, respectively, which mechanisms are so mounted on and relative to the aileron actuating means that vertical deflection of an aileron will not interfere with or materially vary the adjusted position of a tab relative to the aileron in any position to which the aileron may be deflected.

With the up-only aileron embodying the principles hereinbefore generally referred to, my invention further provides, as a feature thereof, the combination with such type of aileron of a fullspa-n wing flap designed and mounted for lowering and raising about a remote hinge axis spaced forwardly from the leading edge thereof, and for rotation in lowered positions about a balance axis intermediate the leading and trailing edges of the flap with the portion of the flap forward of such balance axi providing an aerodynamic balance; the flap of such design and mounting being further characterized by a progressive angular displacement, relative to the wing, as the flap is bodily lowered first about the remote hinge axis, and then about the balance axis to its position of maximum angular displacement, and by the spacing of the leading edge of the flap from the under surface of the wing when the flap is lowered about the remote hinge axis to form a passage for flow of air between the wing and flap.

With the foregoing general features, characteristics and :ob'jects in view, as well as various others that will be apparent from the following explanations, my invention consists in certain novel features in design, arrangement, combination and construction of elements and parts, all as will be more fully and particularly referred to and specified hereinafter.

Referring to the drawings in which similar reference characters refer to corresponding parts and elements throughout the several figures:

Fig. 1 is a view in top plan, more or less schematic, of an airplane with a lateral or roll control system of the up-only type, embodying the principles and features of my invention, mounted and installed thereon; portions of the operating mechanisms for the right wing aileron being more or less diagrammatically shown, as associated with the pilot-controlled actuating memher for the system;

Figs. 2 and 2a constitute a View in top plan of the aileron operating mechanisms constituting the lateral or roll control system for the right wing aileron, with portions of the mechanisms for operating the left wing aileron shown, all in association with the pilot-controlled operating member for the system; the mechanisms being shown in full lines in their positions with the right wing aileron in its bodily-raised position, approaching maximum bodily-raised position;

Fig. 3 is a view in vertical transverse section, taken as on the line 3-3 of Fig. 1, through the right wing aileron and the portion of the wing forward of such aileron, with the aileron actuating mechanism shown in elevation in full lines, with the aileron in its raised position approaching maximum bodily-raised position, the neutral position, and the maximum angularly-deflected position being shown in dotted lines;

Fig. 4 is a vertical transverse section, similar to the view of Fig. 3, but taken as on the line 44 of Fig. 1, and showing a trim tab and its adjusting mechanism mounted on and operatively associated with the right wing aileron A; the

aileron beingshown in full lines in a bodily-raised position corresponding to Fig. 3, with the trim tab in an adjusted downwardly-deflected position relative to the aileron;

Fig. -5 is a vertical transverse section through a wing showing a trailing under-surface wing flap of my invention with portions of its operating mechanism, the flap being shown in full lines in its lowered position below the wing, and being also shown in dotted lines in normal raised neutral position and in its maximum downwardlycleflected position;

Fig. -6 is a detailed view in top plan of the trailing or rear end portion of a hinge arm 4 with the upper or top wall of such arm removed or broken away, and showing particularly the operative connection of such arm to the aileron and the connection of the toggle linkage and parallel linkage of the aileron actuating mechanism to such arm and to the aileron respectively; and

Fig. '7 is a detailed view in vertical transverse section through a hinge arm 4, showing the channel or U-shape of such arm in cross section and being taken as on the line 1-1 of Fig. -6.

An aerodynamical, structural and mechanical adaptation of an up-only aileron type of lateral or roll control system embodying the principles and the various features of my invention is disclosed in the accompanying drawings, as applied to an airplane having the wings thereof provided with full-span trailing under-surface wing flaps of a type and design of my invention with the up-only ailerons of the control system and such full-span flaps, positioned therebeneath in operative aerodynamic and structural relationship and association. However, an up-only aileron type of lateral control system of the invention is not limited or restricted to use .in combination or association with full-span wing flaps, or flaps positioned beneath the ailerons of such system, but is equally adapted to use on and with wings without flaps or wings having partial-span flaps, with fixed wing structure beneath the ailerons of the system, all as may be desired or found expedient. The expressions 'of the principles and various feature of the invention presented by the illustrated adaptions and embodiments thereof, are to be considered purely by way of exemplification, and not in all respects by way of limitation, such adaptations and embodiments being here primarily disclosed for the purpose of explaining and describing the basic principles and features of the invention to enable those skilled in the aeronautical art to understand the same. It is to be understood that the basic principles and the various features of the invention are capable of a variety of other aerodynamical, structural and mechanical expressions, as will be readily appreciated and understood by one skilled in the art from the following explanations of the invention and of the disclosed examples thereof.

An up-only aileron type of lateral or roll control system is disclosed in the present example, as applied to and embodied in an airplane, referring now to Fig. 1 of the drawings, that includes the body or fuselage F, a portion only of which is shown, and opposite wings W with the up-only ailerons A of the system mounted thereon as trailing portions of the upper surfaces of these wings. An operating control system is provided by which such opposite wing ailerons A may be alternately upwardly deflected, respectively, from their normal neutral at-rest positions, with the aileron opposite the one deflected, maintained in its neutral position against deflection during and throughout vertical deflection of the other aileron.

An up-only aileron A designed in accordance with the principles of my present invention may embody, referring now particularly to Fig. 3 of the drawings, a member of airfoil section, mounted and positioned on a wing W so as to form a trailing portion of the upper surface of the wing when the aileron is in its normal neutral control position, as shown by dotted lines in Fig. 3. The aileron A may be of any usual or desired type of construction such as a construction that includes the spar or beam I, disposed spanwise thereof intermediate the leading and trailing edges, and the chordwise ribs or formers la, together with a skin or covering that provides the upper surface lb and the lower surface for the aileron A. It so happens in the present example, that the aileron A is formed with its under surface to of greater camber than the upper surface lb which upper surface, with the aileron in neutral position, forms a portion of the trailing upper surface of the wing W, and carries out the normal airfoil section and contour of such wing upper surface, with the trailing edge of the aileron forming a portion of the trailing edge of the wing.

An aileron A is mounted on a wing W for upward movement only from its neutral position to control positions above and angularly displaced relative to the wing, and for corresponding downward movement from its control positions back to neutral, but may not, in the present example, be displaced downwardly from its normal neutral position; thus providing an aileron of the truly up-only type as distinguished from those types of up-only aileron that are mounted for a relatively slight downward displacement from normal neutral control position when the opposite aileron is upwardly deflected, although my invention is not, of course, limited to such so-called true up-only aileron type of the present example. Following the teachings of my invention, the aileron A is mounted for rotation about a balance axis 2 .disposed spanwise of the aileron intermediate its leading and. trailing edges, to thereby form and provide that portion B of the aileron A, extending forwardly of such axis, as an aerodynamic balance. Preferably, as in the example hereof, the balance axis 2 about which aileron A is to be rotated for upward angular deflection to control positions, is located spaced rearwardly from the leading edge of the aileron, a distance equal to approximately. 40% of the aileron chord in order to obtain a balance portion of maximum area and chord. Obviously, my invention is in no sense limited to the particular percentage of the chord at which the balance axis is located rearwardly from the leading edge of the aileron, as this distance may be varied in accordance with the particular conditions of the design of each particular installation and more or less in accordance with the control forces or hinge moments that are to be overcome.

With the aileron A mounted for rotation about the balance axis 2, with the balance portion B extended forwardly thereof and having an appreciable chord relative to the chord of the aileron, in order to obtain the maximum balancing effect from the balance B when upwardly deflecting the aileron to control positions, it is desirable to avoid blanketing any portion of the beam I.

balance B from the air flow rearwardly over the upper surface of the wing by structure of the wing forward of the aileron. If an aileron A of the up-only type is rotated about the hinge axis 2 when the aileron is in normal neutral control position, not only would downward deflection of the balance B position the leading edge portion of the balance below the upper surface of the Wing, but such deflection would also result in structural interference between the balance and wing structure beneath the balance.

Therefore, in accordance with a further feature of my invention, the aileron A is mounted to be bodily raised about a hinge axis 3 spaced a distance forwardly of and remote from the leading edge or balance portion B of the aileron, prior to upward deflection of the aileron to any appreciable degree about the balance axis 2. The location and forward spacing of the remote hinge axis 3 is such that the aileron A can be swun upwardly about such axis to a position angularly deflected relative to the wing and raised a sufficient distance above the wing structure adjacent the aileron, so as to fully expose the aileron and the balance B to the air flow over the upper surface of the Wing, throughout the range of vertical deflection of the aileron about the balance axis 2. This raised, angularly-deflected position of an aileron A about the remote hinge axis 3 is disclosed inrfull lines in Fig. 3 of the drawings;

while the upwardly-deflected control position of the aileron, about the balance axis 2, is disclosed in dotted lines in Fig. 3, from which it will be readily apparent that the balance B is at all times throughout vertical deflection about the balance axis 2 exposed to the air flow over the wing, so that the maximum balancing forces may be developed thereby acting about the balance axis 2 in a direction to aid upward deflection of aileron A.

An up-only aileron A of the embodiment hereof is mounted and supported on the hingearms 4 and 4' which arms at their forward ends are pivotally mounted for rotation or vertical swinging about the remote hinge axes 3, respectively, by means of horizontally disposed hinge pins and suitable anti-friction bearing assemblies 3a attached to and supported on suitable fixed structure of the wing W at a relatively slight distance below the upper surface or skin of the wing, and spaced forwardly a distance from the aileron A, as will be clear by reference to Figs. 3 and 4 of the drawings. The hinge arms 4 and 4' are disposed chordwise of the wing, spaced suitable distances apart along the span of the aileron and extending rearwardly from the pivotal mountings 3a, respectively, to the aileron A and terminating at their rear ends, spaced a slight distance forwardly of the aileron spar or The upper surface of the wing W is slotted or cut away to receive the hinge arms and to permit of vertically swinging the arms, while the aileron is vertically slotted or cut away to receive the rear end portions of the hinge arms, and to permit of the vertical rotation of the aileron on and relative to such arms without interference therefrom. Any desired number of hinge arms 4 and 4' may be provided along the span of an aileron A, the number usually being dependent upon the length of span of any particular aileron installation. The aileron hinge arms 4 and 4 are preferably formed of U or channel shape in cross section, with the closed side of the section forming the upper side of friction bearings.

hinge pins 5, are fixed tothe aileron spar I at I over the wing upper surface. position of aileron A is shown by full lines in ,Fig. 3, and .it will be apparent that when the aileron is in such raised position the balance B erally differ only-in-tlieir respective widths,the arm or arms' I of an installation being of greater width forthe purpose of operative connection and association of the aileron actuating mechanis rn' thereto and-therewith, while an arm 4' is of lesser width, in that such arm need only be associated with and carry a portion of an aileron trimming tab adjusting mechanism to be referred to and described hereinafter.

An aileron A is mounted in position on and extending across the rear ends of the spaced hinge arms l'and i for vertical rotation on such arms about the aileron balance axis -2. As an instance of the form which such pivotal mounting of an aileron A on-the hinge arms may take, ref- ;erence is made particularly to Fig. 3 of the drawings, in which a forwardly extended bracket member 2a is shown fixedto the spar or beam I of the aileron. Such bracket 2a includes the vertically disposed, horizontally spaced andforwardly extended arms 2?) having the horizontal hinge pin 5 mounted thereon between the forward ends thereof in any suitable or desired anti- Brackets 2a, carrying the spaced intervals therealong, corresponding toand aligned with the hinge arms 4' and I, respectively, and the rear ends of these "bars are mounted on'and connected tothe hinge pins-5 with such pins forming and defining the balance axis 2 on and about which the aileron A-is rotated ,in carrying out the vertical deflection of the aileron in accordance with the'invention.

Thus, with'the aileron 'A mounted and supported on the hinge arms 4' and 4 for rotation fthereon about the balance axis 2 by upwardly swinging the hinge arms 4 and 4'- about the remote hinge axis 3, the aileron A can be bodily raised from its normal neutral position forming a portion of the upper surface of the normal contour of the wing W to a position raised above the wing, fully exposed to the air flow rearwardly Such bodily raised is fully exposed to the airflow forthe reaction ofthe latter thereonthroughout vertical rotation of the aileron about the balance axis to upwardly deflect the aileron to control positions. The air flow rearwardly over the wing will react upon the upper or forward surface of the balance B to force such balance B downwardly,

and thus develop forces acting about the balance axis in a direction to aid in the upward deflection of the aileron A. It will be apparent that as the upwarddeflection of the aileron progresses, with corresponding downward and rearward deflection sition. about the balance axis 2, should be possibleas a continuous, uninterrupted and progressive' movement, without time lapse in. changing the movement ofthe aileron froma movement about the remote hinge axis'3 to a movement about-thebalanceaxis2. Similarly, the lowering of the aileron from-any upwardly deflecte'd control position'about-the balance axis -2 followed by bodily lowering of the aileron-about the remote hinge axis in order to-return the aileron-to normal neutral position, should be capable of being carried out as a continuous, uninterrupted and progressive movement.

For the purpose of actuating an up-only aileron A in accordance with the invention, I have provided an arrangement of mechanism for bodily raising and'lowering such an aileron about its remote hinge axis, and -;for vertically rotating the aileron about its balance ax is,'to and from control positions. Thismechanism, in the particular example hereof, includes a toggle linkage forbodily raising and lowering the aileron about the remote hinge axis 3 and an associated parallel linkage for vertically rotating the aileron about the balance axis 2. Referring now to Fig.3 of

the drawings, the toggle linkage includes a bell crank I0, mounted for vertical rocking about a horizontally-disposed bearing pin II, which pin is, mounted on and supported between the spaced, rearwardly-extending plates orarms of a bracket I, that is fixed to and extends rearwardly and upwardly from the rear wing spar 6 of wing W.

The bell crank supporting bracket I, formed by the spaced arms Ia. and lb, is, in this instance, disposed in a vertical position beneath an aileron hinge arm 4, with the upper end of the bracket spaced a distance below the wing upper surface. (See Fig. 3.) The bracket-I is offset laterally relative to the longitudinal axis of the arm '4, to a position in proximity to the adjacent side wall of the arm but spaced a sufficient distance therefrom to. provide operating clearance for the end or head of the bearing pin. or. bolt I I for the bell crank III, as clearly shown by Fig. 6 of the drawings. In its lowered, neutral position the hinge arm'fi receives the bell crank arm Illa,v the bearing bolt I I and the upper ends of arms Ia and-I-b of bracket I, between its side walls, with the upper or top side wall of arm- 4 having clearance space with such elements-of the bracket and bell crank assembly. The upper and rearwardly-disposed arm Illa of bell crank I0, is disposed and terminates with itsrear end spaced a distance below the leading edge portion of aileron Aand balance B when the latter is in normal, lowered, neutral position, and this endof' bell crank arm lifla is pivotally connected to the hinge arm 4' thereabove by, a link I2. The lower end of'link I 2 .iscoupled to theendof arm Illa. by a bearing pin or bolt I4 while the upper end of thislink is pivotally connected, to the hinge arm 4 by a bearingbolt or pin I5, whichpin may be ,mounted extending between and supportedbythe oppos ite.side walls of the channel section hinge. arm 4; Suitable washers, sleeves or otherspacing members I5a (see Fig. 6) may b m lo e to prop os tion theupper end .of link I.2 on pin I15 relative to the hingqarm side walls. Thus, with the toge l nk forme by ellc an w n ink. I vertical rocking of thebellcrank ID will, through the medium of thelink I2, raiseand lower hinge arm 4 to thereby raise and lower aileron A, sup ported onsaid hinge arm, to.. andi from its position raised bodilyabove thewing.

An actuating rod. I6 .of the push-pull type is piyotally coupled at its rearward end, to the lower or free end of the depending arm Illbof bell crank I0 and this rod I6 extends-forwardly into the wing,-- through rear spar-6, the latter being suitably 'cut away to receive the rod and permit operating movements thereof without interference. Horizontally disposed within the wing, a distance forwardly of rear spar 6, and in this instance forward of the vertical plane passing through the remote hinge axis 3, a bell crank I! is mounted in horizontally disposed position for swinging about a vertical axis provided by a suitable bearing pin Ila. The bell crank I1 is supported by any suitable bracket or other supporting structure (not shown) in the desired position and location within the wing W. The bell crank Il, referring to Fig. 2a of the drawings, in connection with Fig. 3, includes a cross arm lib in neutral position generally disposed chordwise of the wing, with the crank arm IIc extending generally rearwardly and outwardly therefrom relative to the wing, at an acute angle to the cross arm, for rotation about the axis provided by hearing pin Ila. The rear end of this arm Il'c is pivotally coupled to the forward end of the actuating rod I5 by means of a vertically disposed bearing pin I'Id mounted in arm IIc, with a suitable anti-friction bearing of the self-aligning type mounting the end of rod I6 on such bearing pin. Rocking or swinging bell crank I 'I about bearing pin I'Ia in a clockwise direction, referring now to Fig. 2a, forces rod l6 rearwardly to thereby rock bell crank I0 to swing arm Illa thereof upwardly and through link I2, to raise hinge arm 6 and thereby swing such arm about the remote hinge axis 3 to bodily raise aileron A from its neutral position to a position spaced above the wing and exposed to the air flow, for rotation of the aileron about its balance axis 2 for vertical angular deflection thereof relative to the wing for control. The reverse movement of the toggle linkage to lower aileron A to neutral position is accomplished by rotating crank H in an anti-clockwise direction to swing arm I'Ic thereof to draw rod l6 forwardly and thus rock crank I9 to lower hinge arm 4 and the aileron A, supported thereon to neutral position of the latter.

The arrangement of the toggle linkage, referring now to Fig. 3, is such that as crank I0 is rocked to swing arm Illa thereof upwardly and raise aileron A, the crank arm la and the connecting link l2 move toward straight-angle relationship. In the maximum raised position of the aileron A, the foregoing arm llla and a link I2 forming the toggle linkage, very nearly approach straight-angle relationship so that but a minimum of the control forces transmitted to the actuating mechanism by upward deflection of the aileron A about its balance axis, into the air flow, will be transmitted through crank Ill and its actuating mechanism to the control system. The arrangement of the toggle mechanism is such, however, that even in raised position of the aileron A about the remote hinge axis 3, straight-angle relationship is never attained between crank arm IM and link I2, so that this aileron raising and lowering mechanism remains reversible throughout its full range of operation.

An aileron A of the up-only aileron system of this invention is disclosed in dotted outline in its lowered normal neutral position in Fig. 3 of the drawings, and the bell crank I0 and link I2 of the toggle linkage are shown by dotted lines in their positions for this neutral position of aileron A. Aileron A of Fig. 3, with the toggle linkage and associated actuating means, is shown in full lines in position with the aileron partially raised but approaching its maximum raised position; In the arrangement of the present example the hinge arm 4 of an aileron A is raised or swung upwardly about the remote hinge axis 3 through approximately 11 in order to raise the aileron A a sufficient distance above the wing to permitof upward deflection of the aileron about the hinge axis 2 without blanketing balance B and in order to give ample operating clearance between the wing structure and the leading edge of balance B, in the maximum upwardly-deflected position of aileron A.

However, the range of upward swing of the aileron hinge arms and the distance to which the aileron A is bodily raised above the wing on sucharms, is a matter of choice dependent upon the design and construction factors of each installation and the invention is in no sense limited or restricted to the foregoing angular range of upward swing of aileron A about the remote hinge axis 3, of the present example. As the primary purpose of bodily raising the aileron above the wing is to render the balance B thereof fully effective, it may, therefore, be said that it is preferable to limit the range of upward swing to that range necessary to attain this end, in the average installation. Further, while the aileron, when so bodily raised about the remote hinge axis, is angularly displaced relative to the Wing, therefore, has started to function as a lateral or roll control surface; yet, the angular deflection is of necessity relatively small and the rolling moment developed thereby cannot be large. This fact is, however, taken advantage of in that the control forces, or hinge moments developed during the bodily raising of the aileron A about the remote hinge axis 3 and prior to the effective operation of the balance B by upward deflection of the aileron about the balance axis 2, will be of such small magnitude as to not interfere with the said operation of the control system through this initial range of aileron angular deflection, prior to upward deflection of the aileron about the balance axis 2.

The actuating mechanism for an up-only aileron A also includes a parallel linkage arrangement for rotating the aileron A about the balance axis 2 in vertically deflecting the aileron to and from control positions. This parallel linkage is associated with the hereinbefore described toggle linkage for bodily raising and lowering the aileron to and from its neutral control position. This association is preferably such a one as in the examples hereof in which provision is made for initiation of the rotation of the aileron to upwardly deflect the same about the balance axis prior to the bodily raising of the aileron about the remote hinge axis to its maximum raised position, so that upward deflection about the balance axis takes place simultaneously with and during the upward movement of the aileron about the remote hinge axis.

The arrangement and operative coupling and association of the parallel linkage with an aileron A and the toggle linkage therefor is shown, particularly, in Fig. 3 of the drawings, and includes a crank I8 fixed to the aileron wing spar I, and extending forwardly and downwardly therefrom. A bolt I811 is secured extending transversely through the free end of crank arm l8 and a distance outwardly beyond opposite sides thereof, to provide opposite bearing pins at the free end of the crank. This crank arm I8 is flxed to aileron spar I between the spaced arms of bracket 2a to which the rear end of a hinge arm 4 is pivotally connected, in proximity to the side wall of the arm 4 opposite the side wall thereof adjacentthe bell crank H]. A bell crank 19 is pivotally mounted on and depending from the bearing pin 3a upon which the forward end of a remote hinge bar 4 is pivotally mounted, which pin forms the remote hinge axis 3 about which the aileron is bodily raised. This bell crank l9 is'formed with a depending crank arm I 9a and with a depending crank arm lb of greater length than the 'arm Illa, so that, the end of arm 1% terminates a distance below the end of arm [9a with these two arms in relatively slight angular relationship oncumferentially about the remote hinge axis 3. The crank arm Hla is operatively coupled and connected with the crank I8 of aileron A by a rod 20, this rod being pivotally connected at its forward end to the crank arm ISla by a horizontally-disposed bearing pin 20a andbeing pivotally coupled at its rear end to the bearing pin 18a at the forward end of the bracket IS. The distance between the remote hinge axis 3 about which crank arm [9a rocks and the bearing pin 28a at the lower end thereof to which the forward end of rod 20 is connected, is the same as and equivalent to the distance between the balance axis 2 of the aileron A and the axis of the bearing pin lBa of the crank !8 to which the rear end of rod 28 is connected. Thus, a parallel linkage is formed by hinge arm 4 and actuating rod or link 20 with the cranks l8 and 19a pivotally connecting the adjacent opposite ends, respectively, of arm 4 and rod 20, so that, rocking of the crank I9 about the remote hinge axis 3 will, through the medium of the link or rod 20, rock crank [8 to thereby rotate the aileron A about its balance axis 2.

The parallel linkage for each aileron A is operated to vertically deflect the aileron about its balance axis by an actuating rod 2| pivotally coupled and connected to the depending arm I91) of bell crank 19 by a suitable bearing pin Zla. Actuating rod 2i extends forwardly through the wing, W to a bell crank 22 that is mounted in horizontallydisposed position for swinging about a vertical axis provided by a bearing pin 22a. This bell crank 22 includes a main cross arm 22b disposed generally chordwise of the wing, together with the crank arm 22c extended therefrom generally forwardly and inwardly of the wing, and the forward end of actuating rod 21 is pivotally connected to the end of crank arm 22c by a vertically-disposed bearing pin 22d, so that anticlockwise rotaticn of the bell crank forces actuating rod 2i rearwardly to rock bell crank I9 and thus operate the parallel linkage through rod 20 to upwardly deflect aileron A about its balance axis 2.

It is to be here noted that by utilizing a channel or U-section hinge arm 4, and providing such hinge arm of a suflicient width and by utilizing a bell crank in of a material of relatively thin section, the operative association an r ative assembly of the toggle linkage and the par lel linkage with this arm, may be carried out in such 'a way as to permit a compact assembly while attaining operating clearance for the various elements of these linkages and the hinge arm. The rear wing spar 6 is, of course, suitably slotted or cut away from the upper edge thereof downwardly a distance, to give operating clearance for the hinge arm 4 and for the rod 28 of the parallel linkage. With the aileron A in its'lowered, neutral position, the hinge arm 4 is disposed substantially within the contour of the normal wing section, and the channel section hinge arm is positioned over and receives the bell crank ID, with the rod 2!] of the parallel linkages moved downwardly past and clearing the crank I0 and its bearing pin or bolt I I. v

The opposite ailerons A, each with its actuating mechanism consisting of the associated toggle and parallel linkages, are operated, in accordance with the invention, by a pilot-actuated control mechanism, operatively coupled with the aileron actuating mechanisms to form, with such mechanisms and the opposite ailerons A, a lateral or roll control system embodying the principles of the invention. As an example of control mechanism for alternately actuating the mechanisms r for vertical deflecting the opposite up-only ailerons of the system, reference is now made to Figs. 1, 2 and 2a of the drawings. Any usual or other desired pilots control member or element, such as a control wheel C more or less diagrammatically shown in Fig. 1, is provided at any suitable location or control point in the body or fuselage F and control cables 23 are connected therewith for actuation thereby. These control cables 23 are carried from the control wheel C in any suitable or usual manner, and extend in this instance, in horizontally-disposed parallel relation rearwardly to a bell crank 24 that is located in a central position within the fuselage F intermediate the inner or root ends of the opposite Wings W, or within the center section for the opposite wings W, in accordance with the particular conditions of the design of airplane in which the system is installed. The bell crank 24 is mounted in horizontally-disposed position for rocking or swinging about a vertical axis provided by the bearing pin 24a with the main cross arm of this bell crank disposed generally transversely of the fuselage F, and having the cables 23 from control wheel C connected to its opposite ends, respectively.

Bell crank 24 is provided with the rearwardlyextended crank arms 24b and 240 which arms are radially disposed from the bearing pin 24a for rotation thereabout as an axis, and diverge outwardly and rearwardly from such axis in angular relationship with their rearward ends spaced apart horizontally. The bell crank 24 in the arrangement of the particular example hereof, is mounted'to swing in either direction from neutral about the bearing pin 24a so that by movement of the control member such as the Wheel C, the cables 23 are operated to rotate bell crank 24 either in a direction clockwise or anticlockwise about the bearing pin 24a in accordance with the direction of rotation of control wheel C, to thereby swing crank arms 24b and 240 to the'left or to the right, respectively.

The hereinbefore described aileron actuating mechanism provided for each opposite wing aileron A is operated from the bell crank 24 through an arrangement of reciprocal mechanism that includes a parallel linkage embodying a lever bar 25 mounted in horizontally-disposed position for rotation about a vertically-disposed bearing pin 26, with this lever arm extending rearwardly from the bearing pin in a direction generally chordwise relative to a wing when the control system is in its neutral position. A bell crank 21 is mounted on the bearing pin 26 for rotation thereon in a horizontal plane and includes main cross arm 28 with a crank arm 29 extended inwardly therefrom radially of the axis formed by the bearing pin 26. The rear, free end of the lever arm 25 has a bell crank 30 pivotally mounted for rotation thereon about a vera ainst tical axis provided by a bearing pin- 31 carried by the lever arm 25, so that this crank 35 has rocking movement about pin 3| independently of lever arm 25, but is bodily moved with and carried by arm 25 when the latter swings about its bearing pin 25. The bell crank 30 includes an: inwardly-extended crank arm 32 and an outwardly and rearwardly-extended crank arm 33. Crank arm 32 is connected by a rod or link 34 with the inner free end of crank arm 29 of bell crank 21, this rod or link 34 being pivotally coupled to crank arm 32 by bearing pin 35 and to crank arm 29 by bearing pin 35. The distance between the bearing pins 3| and 35 of crank arm 32' is the same as and equal to the distance between the bearing pins 26 and 35 for crank arm 29, and the distance between the bearing pins 35 and 35 for rod 34 is the same as the distance between the bearing pins 25 and 3t for thecranks 21 and 30 of lever arm 25. Hence, rod or link 34 and lever arm 25' are maintained in parallelism, and crank arms 29 and 32 are maintained in parallelism with the result that these connected elements form a parallel linkage for transmitting movement of the bell crank 24 upon actuation thereof by the control wheel C, to the aileron actuating mechanism. Movement of the ball crank 24 is transmitted to the parallel linkage by the actuating rod or link 3'? that is pivotally connected at one end thereof to the rear, free end of crank arm 241) by a bearing pin 38 and pivotally connected at the opposite end thereof to the outer free end of arm 33 f crank 30 of the parallel linkage by the bearing pin 39 mounted on and carried by said crank arm 33.

A stop member 40 is mounted on and preferably adjustably secured to, any suitable or desired fixed supporting structure (not shown), with this member 45 positioned adjacent the rear end of lever arm at the inner side of such arm so as to be engaged by the arm to maintain the same in a pre-determined position against inward swinging from such position. A compression spring or other force-exerting unit 4| is pivotally connected to the lever arm 25 at the outer side thereof at 42, substantially opposite the stop member 43 in this instance, and this spring or force unit extends outwardly therefrom and is secured at its outer end at 43 to a suitable fixed structure (not shown). The spring unit 4! is arranged and mounted to continuously exert a force acting on the lever arm 25' to swing this arm inwardly and normally maintain the same against the stop member 40 and thereby normally restrain the arm from outward swinging about its bearing pin 26. In order to swing arm 25 from its position against stop member 40 it is necessary to apply thereto a force of sufficient magnitude to overcome the force exerted by the spring unit 4| and after arm 25' crank arm 24b to the left and through the rod" 31', crank 33 will be rocked to swing arm 32 thereof forwardly. During this operation, the lever arm 25 on which crank 33 is mounted. and carried, will be forced and held against stop member 40" by the forces exerted by the spring unit. 4i and by the forces applied to crank 33 by rod3Yl, such forces acting. onthe rear, free end of .arm 25 in a direction tending to swing this arm inwardly of the wing W aboutthebearing pin 25' at'the forward end of the am. Forward. swinging of crank arm 32 forces the rod 340i the parallel. linkage mechanism forwardly and crank arm 2.) of the bell crank 21 is thus swung forwardly to rock or rotate bell crank 2! in" a clockwise direction about the bearing pin 26' on which this crank is mounted at the forward end of lever arm-25.

Clockwise rocking of crank 21' is transmitted through cables 44 and 45- to a bell. crank 45, referring now to Fig. 2a, that is located spaced a distance outwardly in the right wing ,W. Bell crank 45' embodies a cross arm 48' and a cross arm 43 with the bell crank mounted in horizontally-disposed position for rotation or rocking about a vertically-disposed bearing pin 41. Cables 44 and 45 are connected betweenthe forward and rear ends, respectively, of the cross arm 48 and the forward and. rear ends of the cross arm 28' of the bell crank 21, so that rocking of bell crank 21 correspondingly rocks bell crank 43' about its bearing pin 41. The cross arm 49; of bell crank unit 45 is disposed in angul'ar relation to cross arm 48' and provides the generally forwardly and inwardly disposed crank arm- 50 for actuating the toggle linkage of the actuating mechanism for aileron A of this right wing W, and provides the oppositely extending generally outwardly and rearwardly disposed crank arm 51 for operating the parallel linkage of such aileron actuating mechanism.

Adjacent, but disposed outwardly of the" right wing W, from the bell crank unit 46, a bell crank 52- is mounted in horizontally-disposed position for rocking about the vertical bearing pin 53; with this bell crank embodying a main cross arm 54 Bell crank 52-includes a crank arm55 angu larly disposed relative to main cross arm 54 and extending radially from bearing pin' 53 in a general forward and inward direction relative to the wing. A link or connecting rod 56 extends between and pivotally connects the end'of crank arm 55 of bell crank 52 with the'end' of the crank arm 5! of bell crank 45. The crank arms- 5 and 52 extend generally in opposite directions from their respective pivot points, so that the direction of rotation imparted to the bell crank 52' by rotation or rocking of bell crank 43 is always oppositethe direction of rotation of the latter. The connecting rod or link. 56' is pivotall'y coupled at its'inner end to the outer end of crank arm 5! by a bearingpin 51 and is cou pled at its opposite outer end' to the'en'd of crankarm 55 by a; bearing pin 58'; suitable anti-friction bearing-s being carried by the opposite ends of link 55- for mounting upon these bearing pins, respectively. The bell crank 52 is operatively coupled with the bell crank 22 from which the parallel linkage of the aileron actuating mechanism is operated. The'bellcrank- 22 is spaced? a distance outwardly in the right wing W from bell" crank 52, with these bell cranks aligned spanwise of the wing, and the respective cross arms'54 and 43' thereof of the'same length. The operative-connection of bell crank 52 with bell crank 22 is carriedout in this instance,- through the medium of the cables 59- and 60 that are pivotally connected between the opposite ends, respectively, of. the cross arm 54 of crank 52 and the cross arm 22h ofbell crank 22.

The bell crank IT for operating the toggle linkage of the aileron actuating mechanism, is also operated by and from the bell crank 46. In this particular example, the bell crank 11 is mounted in the wing W spaced a distance rearwardly from bell crank 22 and offset inwardly a slight distance therefrom, and this bell crank I1 is operatively coupled with the bell crank 6| that is spaced a distance inwardly of the wing from bell crank 11 but aligned spanwise of the wing therewith. The bell crank 6| is disposed within the wing to the rear of, but intermediate th bell cranks 46 and 52, and includes a cross .arm 62 that is connected at its opposite ends with the vopposite ends, respectively, of the cross arms Nb of bell crank I! by the cables 63 and 64.

.The bell crank 6| is mounted in. horizontally-disposed position for rocking about a vertical pivot or bearing pin 65 and is provided with a crank arm 66'that extends radially from bearing pin 65 at a slight angle relative to cross arm 62 and in a rearward direction relative to the wing. Bell crank 61 is operatively coupled with the bell crank 46 through the medium of a connecting rod. or link 61. This connecting rod or link 61 is pivotally connected at its forward end with crank arm 56 of bell crank 46 by means of an offset bearing pin 68 and is operatively coupled at its opposite end with the rear end of crank arm 66 by an offset bearing pin 69, the arrangement being such that connecting rod or link 61 is disposed at and spaced inwardly of the wing from the ends of the crank arms 50 and 66. Preferably the ends of rod 61 are provided with suitable anti-friction bearings by which they ar mounted on the bearing pins 68 and 69, respectively. By this arrangement, clockwise rocking of the bell crank 46 about the bearing pin 41 swings crank arm 50 forwardly and through the connecting rod or link 61, rocks crank arm 66 of bell crank 6| inwardly and forwardly to rotate the bell crank 61 in a clockwise direction. Clockwise rotation of bell crank 6i rotates bell crank l1 throughcables 63 and 64 in a clockwise direction to thereby swing crank arm [1c in a clockwise direction to force actuating rod 16 rearwardly to actuate the toggle linkage to raise the aileron A of this right wing W, in the manner as hereinbefore described.

,In the control operation of the disclosed system, referring now particularly to Figs. 1 and 2 of the drawings in which the right wing aileron is disclosed, if the pilot desires to raise this right aileron, in order to lower the right wing, the control element or wheel C is operated in a clockwise direction to swing bell crank 24 in a clockwise direction about its bearing pin 24a. Clockwise rotation of bell crank 24 swings or rotates crank arm 24b to the left, referring now to Figs. 2 and 2a of the drawings, and through rod 3'! rocks crank 30 in a clockwise direction, with the forces reacting on arm 25 in a direction to maintain this arm in position engaging the stop member 40 and held thereby against inward swinging or displacement, this arm 25 also being subjected to the forces exerted by spring 4|, acting thereon to maintain the arm against the stop member 40.

Bell crank 24 is designed and mounted for rocking through 50 in either direction about its bearing pin 24a in this specific instance, and the design and arrangement of the parallel linkage through which the right aileron A is actuated to control positions is such that a movement of bell crank 24 will result in a 20 movement of the crank arms 32 and 29 of the pare allel linkage. Thus, with the operation of the system to raise the right aileron A for control, upon rocking bell crank 24 in a clockwise direction through the first 10 of its movement, the right wing parallel linkage has the crank 30 rocked in a clockwise direction about its hearing pin 3| through 20 to thereby actuate the parallel linkage to rock crank arm 29 and the bell crank 21 in a clockwise direction through 20 of their range of movement. The bell crank 24 and associated mechanisms for the right wing aileron A are shown in full lines in their respective positions with crank 24 swung through the first 10 of its range of movement in a clockwise direction.

The rocking of the bell crank 2'! through the first 20 by the actuation of the parallel linkage results in rocking the bell crank 46 through the medium of the connecting cables 44 and 45, through 20 in a clockwise direction. This clockwise swinging of bell crank 46 also swings crank arm 50 thereof through 20 of its movement and thereby moves the connecting link or rod 61 forwardly to rock bell crank 6| in a clockwise direction about its axis formed by the bearing pin 65. The relative arrangement of the crank arm 50 of bell crank 46 and the crank arm 66 of bell crank 6| with the connecting rod or link 61 coupled by the offset pivot points between these crank arms is such that this 20 movement of bell crank 45 is translated into substantially a 42 movement of bell crank 6|, to the full line position thereof shown in Fig. 2a, in the specific example hereof. The swinging of bell crank 6| in a clockwise direction in turn swings bell crank I1, through the connecting cables 63 and 64, in a clockwise direction, through substantially a 42 range of movement about its axis or bearing pin [1a, to the full line position thereof as shown in the drawings.

The crank arm l'lc of bell crank 11 is thus rotated or swung inwardly and rearwardly through approximately 42 and forces the actuating rod l6 rearwardly to thereby rock the crank IU of the toggle linkage for the right aileron A, upwardly. Upward swinging or rocking of crank l0 about its bearing pin Hswings the aileron hinge arm 4 to which it is connected by link l2, upwardly about the remote hinge axis 3 to thereby bodily raise this right wing aileron A from its normal neutral position (shown by dotted lines in Fig. 3), to control position raised above the wing and disposed in the air flow over the upper surface of the wing. This raised position of aileron A,

resulting from operation of the pilots control wheel C to swing the bell crank 24 through approximately its first 10 of movement is shown by full lines in Figs. 3 and 4 of the drawings. In this raised position that corresponds to the approximately initial 10 movement of bell crank 24, the aileron A is not as yet in its maximum bodily-raised position, but very nearly approaches this position so that there remains but a relatively small degree of movement necessary to swing aileron A to its maximum raised position. With the aileron A in its bodily-raised position, resulting from the initial 10 movement of the bell crank 24, and closely approaching its maxi-.

mum raised position, it is to be noted that the arm Illa of crank H of the toggle linkage approaches straight-line relationship with the link I2 of this linkage, and while the control forces that will bedeveloped in raising and holding aileron A in its bodily-raised position, will be of relatively small magnitude, yet, due tothe near straight-angle relationship of the foregoing arms Illa and I2 of the toggle linkage, the major portion of such control forces will not be transmitted through the system to the pilots control operating member, such as the wheel C of this example.

Duringthe foregoing actuation of the toggle linkage to bodily raise aileron A about its remote hinge axis 3, the swinging of bell crank 40 in a clockwise direction through approximately 20, swings crank arm rearwardly and through connecting rod or link 58 results in rocking the bell crank 52 in an anti-clockwise direction about its axis 53 to swing the cross arm 54 of this bell crank through only approximately in an anti-clockwise direction to the full-line position thereof shown in Fig. 2a. This 10 of movement of cross arm 54 of bell crank 52 is transmitted through cables 59 and 60 to the cross arm 22b of crank 22, so that this crank is swung in an anti-clockwise direction through approximately 10 of movement. Such rocking of crank 22 swings the crank arm 22c thereof inwardly and rearwardly of the wing to thereby force actuating rod 2i for the parallel linkage of the aileron actuating mechanism rearwardly to rock crank arm I9b of the bell crank I9 that is mounted for rocking about the remote hinge axis 3 rearwardly through approximately 5 of movement to the full-line position of this bell crank l9 shown in Fig. 3. The rearward rocking or swinging of crank arm 19!) rocks crank arm l9a rearwardly to actuate the parallel linkage through rod or link 20 and crank arm l8 torotate aileronA about its balance axis 2 to an upwardly-deflected position, displaced through an angle of approximately 5, as shown by the full-line position of aileron A in Figs. 3 and 4. Thus, in the bodily raised full-line position of aileron A, shown in Fig. 3 of the drawings, the parallel linkage of the aileron actuating mechanism has been simultaneously operated with the bodily raising of the aileron by the toggle linkage so that the aileron has not only been bodily raised, but has also been upwardly deflected through an angle of approximately 5. In order to swing the aileron A to its maximum upwardly-deflected position, shown by dotted lines in Figs. 3 and 4, such maximum position being an angular displacement through approximately the control wheel C is further operated to rock bell crank 2'4 through the remaining 40 of its range of movement in a clockwise direction. Such further swinging of bell crank 24 rocks bell crank 46 and the crank arms 50 and El thereof, in a clockwise direction through the remaining 40 of the total range of swing of of said bell crank. .The swinging of crank arm 5! in a clockwise direction swings bell crank 52 further in an anti-clockwise direction, through the remaining approximately 40 of its 50 of total movement, by means of the connecting rod 5%. Rocking of bell crank 52 then actuates the parallel linkage by means of the bell crank 22, to further upwardly deflect the aileron A through the remaining approximately 35 of its upward deflection to its maximum control position shown by the dotted line position of aileron A in Figs. 3 and 4.

While the upward deflection of aileron A to its maximum control position is being carried out, the rocking of crank arm 50 of bell crank 46 causes connecting rod or link 01 to further rock bell crank 6| in a clockwise direction, but, due to the relationship between the crank arm 50 of bell crank 46 and the crank arm 66 of bell crank Bi" and of-theconnecting rod or link 67, the cross arm 62'- of bell crank 6| is further rocked in a clockwise direction through only approximately 18 of movement. Cross arm Nb of hell crank l'i, together with crank arm H0, is thus rocked through cables and fi thy this 18 of movement of hell crank El and through 18, but with crank arm Ha and the actuating rod It for the toggle linkage approaching straight-angle relationship, as will be clear from the full-line position of these elements in Fig. 2a, the'further rearward movement of rodiii resulting from the 18- movement of crank arm lie is materially reduced, and results in rocking the bell crank I 0 through the remaining relatively small degree of its total range of movement necessary to complete the bodily upward swinging of aileron A into its maximum raised position. This final movement of crank [0a and the connecting link 52 will be relatively slow in relation to the rate of upward deflection of the aileron A about its balance axis 2 through the remaining 35 of the aileron deflection, and the hinge arm 4 and the aileron A will not reach their maximum bodily-raised positions swung upwardly about remote hinge axis 3, until aileron A has been rotated about balance axis 2' to reach its maximum angle of 40 of upward deflection relative to wing W. Even in the maximum raised position of aileron A, crank arm Mia and link l2 will not attain straight-angle relationship and the toggle linkage, therefore, remains reversible.

The aileron A is raised by the toggle linkage to a position fully exposing the balance B of the aileron to the air flow rearwardly over the wing,

. pilot in operating the control system. Due to thedesign, arrangement and mounting of the mechanisms embodying the control system as hereinbefore described, it is apparent that the aileron A can be actuated from its normal neutral and at rest position to its maximum upwardly-deflected control position with the aileron swung or rotated about the separate widely spaced hinge axis 3 and balance axis 2 by a continuous, smooth and uninterrupted movement of the pilots control member, such as the wheel C of the present exraised position between neutral lowered position and its maximum raised position. The angle through which the aileron A is bodily raised from neutral position about remote hinge axis 3 in order to fully expose aileron balance B to the airflow, is suniciently small to require but relatively small movement of the pilots control member C to accomplish, and with the simultaneous angular deflection of the aileron A relative to the wing W resulting from such movement, there is no material lag between the operation of the control and the rolling response therefrom.

The up-only aileron A of left wing W is actuated by an arrangement of mechanisms in all respects identical to the mechanisms of the control system hereinbefore described in detail in connection with the operation of the aileron A of the right wing W, and it is not deemed necessary to describe this duplicate mechanism in detail. In Fig. 2 of the drawings, that portion of the left wing aileron operating mechanism of the system is disclosed that consists of the left wing parallel linkage that is coupled with the bell crank 24 operated by the pilots control wheel C through the operating cables 23, and the elements of this parallel linkage and of those portions of the associated mechanism that are disclosed have been given identical reference numerals as those used for such elements of the corresponding mechanisms of the right wing aileron, except that each of these reference numerals has been primed. For example, the crank arm 240 of bell crank 24 is connected with the bell crank 30 of the parallel linkage for the left wing aileron A by the actuating rod 31, which rod is pivotally coupled at its inner end to crank arm 240 by the bearing pin 38' and at its outer end is coupled to the free end of crank arm 33 of bell crank 30' by the bearing pin 39. The cross arm 28' of the bell crank 21 of the parallel linkage has the cables 44' and 45 connected therewith, which cables correspond to cables 44 and 45 of the mechanism of the right wing aileron, and lead to mechanisms in the left wing W corresponding to those hereinbefore described in connection with right wing aileron A for transmitting aileron actuating movements from bell crank 21 to the left wing aileron A.

The inherent static unbalance of an up-only aileron type of lateral or roll control system is eliminated or substantially reduced in accordance with th principles of my invention, in the particular example hereof, by the application of a force to each of the opposite up-only ailerons A, respectively, of the system, which force continuously acts to bodily raise each aileron upwardly about its remote hinge axis 3 from the normal neutral, at-rest position of the aileron. As an example of one possible method of generating and applying such a force to an up-only aileron, I have provided a spring unit H1, referring now particularly to Figs. 2a and 3 of the drawings, in which such a unit is shown in association with th aileron A of the right wing W of the airplane, the spring unit 10 in this particular example being operatively coupled to the toggle linkage of the aileron actuating mechanism. Such a spring unit ll] may be of the coil, extensile type as here shown, and may be secured at its rear end to suitable fixed structure, such as the wing spar 6, by a pivotal connection 10a and extend forward and be attached to a suitable bracket or fitting 'lllb fixed on the outer end portion of crank arm I10 by a pivotal connection 180. Thus, this spring unit I is mounted in position connected between the fixed attachment point a and the crank arm l'lc for actuating the toggle linkage for raising and lowering the aileron A, so that this unit continuously exerts a force on the crank arm l'lc acting in a direction to swing this arm clockwise about its axis Ha to thereby continuously tend to force actuating rod IS rearwardly to raise aileron A from its normal, a't-rest position. A similar force unit 10 is associated with the opposite left wing aileron A and applies forces continuously acting to raise that aileron from its normal, at-rest position, in the same manner as described in connection with the spring unit 10 for the right wing aileron A.

While I have disclosed in this particular example a spring unit as the means for generating and applying the raising force to an aileron A, it is to be understood that my invention is not limited to any particular type of means or mechanism that may be employed for generating and applying the required forces, but the invention contemplates and includes any suitable or desired means or mechanism adapted to or suitable for this purpose. This feature of my invention broadly consists in the elimination or reduction of static unbalance in an up-only aileron type of lateral or roll control system by the application of a force to an up-only aileron that acts independently of and in addition to the force applied to the system to raise an aileron from its normal, at-rest position by pilot operation of the system; such independent force being primarily applied for the purpose of removing from the system the inertia loads that are encountered in picking up and raising an aileron from its neutral, at-rest position when the system is operated by the pilot. Further, it is to be noted that with the specific type of means of the present example, the force is continuously applied to the aileron, but the invention is not so limited, as, if desired, a type or arrangement of force generating means may be utilized that only applies such force when the aileron is being upwardly deflected.

In order to facilitate a clear understanding of the discussion which follows, and referring again to Figs. 2a and 3 of the drawings, I should like to call particular attention to the fact that when the right wing aileron A has been fully retracted from an upwardly raised, control position to its neutral, at-rest position, rod IE will have been drawn forward to the limit of its reverse-control movement, crank arm Ilc of bell crank unit I! will have been rotated in an anticlockwise direction to the limit of such anticlockwise movement, and spring unit 10 will be fully extended and continuously applying a force tending to rotate bell crank unit I! in a clockwise direction to move rod l6 rearwardly and. raise aileron A. Bell crank unit I! is operatively coupled, through the medium of cables 63 and 64, to a second bell crank unit 6|, as hereinbefore described. It must be clear, then, that if right wing aileron A is in its fully retracted or neutral position, and bell crank unit I! has reached the limit of rotation anti-clockwise, bell crank unit 6| will likewise have reached the limit of its rotation in an anti-clockwise direction. At the same time, the force continuously applied by spring unit I0 tending to rotate bell crank unit I! in a clockwise direction would apply equally to bell crank unit 6| as a force tending to rotate the latter in a clockwise direction. Similarly with bell crank unit 46, which is operatively coupled to bell crank unit 6| by rod 61; and the same conditions would apply to bell crank unit 21 of Fig. 2, which, through the medium of cables 44 and 45, is coupled into this operating mechanism for actuation of the right wing aileron A,

Thus it will be seen that when right wing aileron A is :fully retracted to its neutraLat-rest position, each of several similarly disposed bell crank units in the operating mechanism inter-- mediate the right wing parallel linkage of the reciprocal mechanism and the toggle linkage for the right wing aileron A will reach a limit of rotation in the anti-clockwise direction, coming to rest. in a position which may be called its neutral-control position; also, that the forcegenerated by spring unit H3 is continuously applied to each of said bell crank units tending torotate it in the clockwise and control direction away from its neutral-control position.

Similar conditions, of course, apply -to left wing aileron A, except that in this case the direction of rotation :of the several bell crank units of the operating mechanism or linkage intermediate the left wing parallel linkage of the reciprocal mechanism and the toggle linkage for left wing aileron A is reversed. In brief, when the left wing aileron A has been fully retracted to its neutral, at-rest position, each of the several bell crank units of the said left wing aileron operating mechanism will have been rotated to the limit of rotation in a clockwise direction, and will be at rest in its neutral-control position; while the force generated by a spring unit 19, operatively associated with the toggle linkage for left wing aileron A, will be continuously applied to each of the bell crank units of the left wing aileron operating mechanism tending to rotate such 'bellpilots control wheel C and the opposite ailerons A, referring now particularly to Figs. 2 and 3, are likewise in neutral; with centrally-located bell crank LAdisposed spanwise of the wing; with lever arms 25 and .25 held in the normal, neutral positions thereof, pressed against their respective stops AB and 145' by the action of spring units M and 141 respectively; with bell crank unit 21 at rest in neutral-control position, having been rotated to the limit of movement in an anticlockwise direction; with bell crank unit 2 in the neutral-control, full-line position of Fig. 2, having been rotated to the limit of movement in the .clockwisedirection; and with spring units'lil, operatively associated with opposite ailerons A, continuously applying forces tending to rotate bell crank 21in a clockwise direction and bell crank 2 in an anti-clockwise direction.

Star'ting with such neutral-control position for the-system as a whole, if the pilot now moves the control wheel C in a clockwise direction-the natural movement of such a pilot-controlled element to depress the rig-ht wing and raise the left wing; and if such clockwise-rotation of control wheel C is merely sufficient to rockbell crank 2'4 in a clockwise direction through the first 10 of its movementfrom a neutral-control position; then rod will he moved slightly to the left as shown, bell cranks 3S ,and {21 be rotated in a clockwise direction to the full-line positions here n l err 2. a d i t g a r n A will be raisedf-rom its neutral, at-rest position to the bodily-raised, angularly-defiected, full-line position of Fig. 3, all .as hereinbefore described. But insofar as this movementapplies strictly to actuation of the right wing aileron mechanism, and particularly during the initial stages .of such movement, this clockwise rotation of control wheel 0 -to .rock bell cranks 24, 30 and 21 in a clockwise direction requires no effort on the part of the pilot; because spring unit 10, operatively associated with the right wing aileron operating mechanism, is continuously applying forces tending to rock be-llcranks 2.! and 30 in a clockwise direction, and is thus developing a compression force inrod 31 tending to rock bell crank 24in a clockwise direction. In efiect, then, pilot movement of the oontrol wheel C in a clockwise direction merely-servesto release the potentialenergy of thespring .moperatively coupled. with the -aqtuat ing mechanism for right wing aileron A, andsaid spring unit 10 is thus enabled substantially to lead pilot actuation of the control system to pick up right wing aileron A from its neutral, at-rest position and start it moving bodilyupward about its remote hinge axis 3 to control positions spaced above the upper surface of the wing.

When control wheel C is rotated ina clockwise direction to rock bell crank .24 ina clockwise direction and actuate the right wing aileron A, not onlyis rod 3? moved .to the left, but rod 31, pivotally attached-to the outer, free end of crankarm 2400f :bel-l crank 24, is likewise moved to the left.

This outward movement to the left on the part .of

rod 31 i might .be'e'xpected to rock bellcrank 3B inia clockwise direction about .itslbearing. pin .3 I at :least to the limit imposed by the relationship between .rod 3l andcr-ankarm 33. But crank arm 32' of bell crank 30' is a member ,of the parallel linkage. As such .it must constantly maintain a position parallel to crank arm 29' of bell crank 2 As previously noted, bell crank 2;? is at rest in its neutral-control position, having been rotatedto the limit of movement in the clockwise direction to fully retract left wing aileron A to its neutral, at-rest position. Since crank arm 29' is unable to move any further in a clockwise direction, crank arm 32' of bell crank 301' cannot be rocked ina clockwise direction, and the forcezapplied to the left wing parallel linkage by outwardly-moving rod ,3?! serves to hold left wingaileron A securely in its neutral, at-rest position. Continued rotationof bell crank 24 in a clockwise direction to deflect right wing aileron A about its balance axis to high-angle control positions will cause rod 31 to continue moving outward to "the left while constantly applying forces to the 'left wing parallel linkage tending to preventanti-clockwise rotation of hell crank 2 F to actuate the left wing aileron operating mechanism, to raise left wing aileron A from its neutral position to control positions. Thus, it will be seen that with this type of up-only aileron control system, the aileron opposite the upwardlydeflected aileronis maintained in its normal, neutral, .at-rest position against displacement during and throughout vertical deflection of the other aileron.

'The foregoing discussion implies, in a sense, that the pilot experiences no feeling of control force when moving control wheel C from neutral inthecontrol direction to actuate the right wing aileron operating mechanism to raise the right wing aileron A from neutral to control positions, due to the force generated and continuously applied to said operating mechanism tending to actuate it in the control direction. True, the pilot has no feeling of picking up the aileron from its at-rest position and setting it in motion upwardly to control positions. He does, however, experience a feeling of control force. This is supplied by the force generated and continuously applied by spring unit 4| of the left wing parallel linkage to resist any movement of lever arm 25' away from its normal, neutral position against stop 40'. Clockwise rotation of bell crank 24 moves rod 31 outwardly to the left, as hereinbefore described. The compression force thus developed in rod 31' is transmitted through the medium of crank arm 33 to the rearward, free end of lever arm 25', and the latter is forced outwardly, compressing spring unit 4| and swinging in a clockwise direction about bearing pin 26 and away from its stop 48. Spring unit 4| resists such clockwise rotation of bell crank 24 away from its neutral-control position to rock crank arm 240 in a clockwise direction, to move rod 31 to the left, to force lever arm 25 outwardly away from its stop 40.

Thus, it will be seen that opposing forces are applied to centrally-located bell crank 24 when it is in or near its neutral-control position. Spring unit 10, operatively coupled into the right wing aileron operating mechanism is continuously applying forces tending to rotate bell crank 24 away from its neutral position and in a clockwise direction; while spring unit 4| is continuously applying forces tending to resist rotation of bell crank 24 away from its neutral position in the clockwise direction. The force generated by spring unit 4| and applied thereby to the outer end of relatively long lever arm 25' is designed to slightly overbalance or outweigh the force generated by the spring unit associated with right wing aileron A and made effective through relatively short crank arm 240. Accordingly it must be clear that if bell crank 24 is to be rocked away from its neutral position in a clockwise direction, some force must be added to that generated by the said right wing aileron spring unit 10. This additional force is supplied by the pilot; and the feeling of control force which he experiences when moving the control wheel C from neutral in the control direction to raise right wing aileron A results from the slight differential between the forces of spring unit 10 and spring unit 4| of the opposite aileron mechanisms. At the beginning of such movement away from neutral, the force needed to be exerted by the pilot is slight-so slight, in fact, that the neutral point in the control system would scarcely be noticed by the pilot if he were swinging control wheel C back and forth through neutral. As this movement continues, however, and bell crank 24 is moved farther and farther in the clockwise direction, the pilot will need to exert an increasing amount of force, due to .the increasing magnitude of the force generated by spring unit 4| as it is compressed to a greater and greater extent by the outward swinging of lever arm 25'. In this manner an up-only aileron controlsystem of my invention is given quite a normal, natural feel in the hands of a pilot, for the pilot anticipates the feeling of increasing control force when moving a control element such as wheel C outward from neutral-control position toward the fullcontrol position.

Having moved the up-only aileron control system of my invention to the position indicated by the full lines of Figs. 2 and 3 particularly, if the pilot now wishes to reverse the control operation and return right wing aileron A to its neutral, at-rest position, he has merely to reverse the direction of rotation of control wheel C to rock bell crank 24 in an anti-clockwise direction back to its neutral-control position. This action will serve to reverse the movement of parts in the right wing aileron operating mechanism, as hereinbefore described, and right wing aileron A will be retracted to its neutral, at-rest position.

If the pilot continues this anti-clockwise movement of control wheel C on through neutral, in the control direction to actuate the left wing aileron operating mechanism and raise the left wing aileron A from neutral to control positions, bell crank 24 will be rocked through its neutralcontrol position in the anti-clockwise direction, rod 3"! will be moved to the right to force the right wing parallel linkage outwardly to reversecontrol positions, and rod 31 will be drawn inwardly to the right, thereby releasing the potential energy of spring unit 10, operatively associated with left wing aileron A, to rotate bell cranks 30' and 21' in an anti-clockwise direction, to actuate the left wing aileron operating mechanism, to raise the left wing aileron A from neutral, at-rest position to control positions, all as hereinbefore described for the opposite wing mechanisms.

An important characteristic of a satisfactory aileron control system is that it should automatically neutralize itself if released by the pilot during control operation. Assuming that the up-only aileron control system of my invention, as herein exemplified, has been moved to the position indicated by the full lines of Figs. 2 and 3, if the pilot now releases control wheel C, it is clear that the aerodynamic force applied to the upwardly-raised and angularly-deflected right wing aileron A will alone be sufficient to partially or nearly return said aileron A to its neutral position. As aileron A moves bodily downward, however, the action of the toggle linkage is reversed, and rod I6 is moved forward to gradually extend spring unit and thereby generate the force designed to raise aileron A from neutral to control positions. In these circumstances, aerodynamic force alone can hardly be expected to fully retract right wing aileron A. It will be recalled, however, that spring unit 4| of the left wing parallel linkage is continuously applying forces tending to return the system to its neutral position; and inasmuch as spring unit 4| represents a force of greater magnitude than that of spring unit 10 operatively associated with right wing aileron A, it must be clear that the system will be neutralized even though the pilot is applying no force in the reverse-control direction. At the same time, it should be noted that spring unit 70, through gradual extension, has served as a dampening agent to ease right wing aileron A down into its neutral, at-rest position.

Due to the arrangement of the various mechanisms and their cooperative association, that form and provide the control system, together with the force-applying means for eliminating the inherent static unbalance of the up-only type of aileron, all as hereinbefore described, the pilot can operate the system to raise and lower either aileron A to and from its maximum control position by a continuous and uninterrupted movement of the control system operating member,

such as wheel C. Further, the system can be operated back and forth through neutral to lower one aileron and then raise the opposite aileron, or can ,be operated to raise one aileron from neutral, without any objectionable feel in the control system operating member, because the dead weight and inertia loads that would be imposed on the system by picking up and raising an aileron from its at-rest position are eliminated by the raising forces continuously and independently applied to the opposite ailerons. Thus, one of the serious problems and disadvantages of the up-only aileron type of control system is overcome by a system designed to embody the principles and various features of the present invention.

In order to provide for laterally trimming the airplane to correct for a wing hea y Condition at one side or the other thereof, the invention provides, as a further feature thereof, the combination with opposite ailerons of the up-only type, of trimming tabs mounted on and operatively associated with such ailerons for independent adjustment, together with suitable pilot operated and independently operable adjusting mechanisms for such tabs. As an example of such trimming tabs, and their adjusting mechanisms, as applied to and combined with the uponly ailerons A of the illustrated form of my uponly aileron control system, I have disclosed, referring now to Figs. 1 and 4 of the drawings, a trim tab T mounted on each aileron forming a trailing portion thereof, along the inboard span of the aileron. Each tab T is identically designed and mounted, and it will sufiice to describe the tab T mounted on the right wing aileron A, together with its adjusting mechanism, all as shown particularly in Fig. 4 of the drawings. The tab T is mounted for vertical deflection about a hinge axis disposed spanwise of the leading edge portion of the tab, such hinge axis being formed by a bearing pin H that is carried by a suitable bracket or brackets 12. By swinging this tab T downwardly, at an angle relative to the aileron A, the aileron will, of course, be raised as a result of the airflow reaction on the tab, to thus depress or lower the right wing so as to correct for a condition of lateral unbalance that may be caused by left wing heaviness. Similarly, the trim tab T on the left wing aileron A may be lowered or swung downwardly to an adjusted position to raise such aileron in order to depress the left wing to correct for a condition of right wing heaviness. In the particular example hereof, it is to be noted that the depth of a tab T is greater than the depth of the trailing portion of an aileron, A, and'that clearance with wing structure below the tab to accommodate such increased depth as well as to permit downward deflection of the :tab, is necessary. In thisinstance, the structure beneath an aileron A and its tab T is formed by a wing flap L, and such flap is cut away or recessed to receive the tab when the aileron A and flap are in their normal neutral positions, as shown by dotted lines in Fig. 4.

The opposite aileron trim tabs T are designed and mounted for independent adjustment and a suitable adjusting mechanism for pilot operation is associated with each up-only aileron A. For example, a depending bracket 13 maybe provided suitably fixed or secured to the aileron spar i, and this bracket pivotally mounts at its lower end a compression link or lever 14 which link extends upwardly from bracket l3 and is adapted for swingingthrough a plane chordwise of the wing. A push-pull rod or link 15 is pivotally coupled at its rear end to the trim tab T at a point, in this instance, beneath the hinge axis H of the tab and extends forwardly and is pivotally coupled to the upper end of link 14 by an offset bearing connection Hi. The ofiset bearing 76 that forms the pivotal connection between push-pull rod 15 and the link 14 is so designed that with the trim tab T in its neutral position, the bearing 16 is in axial alignment with the balance axis 2 of the aileron A. Hence, vertical deflection of aileron A about its balance axis 2 may be carried out without moving the trim tab T from its neutral position, the tab remaining with its position relative to the aileron undisturbed and unchanged throughout aileron vertical deflection.

For the purpose of rocking link it in order to angularly deflect the trim tab T relative to aileron A, a pilot operated mechanism is pro.- vided that includes a cable drum H mounted for rotation in a plane spanwise of wing W about an axis disposed chordwise of the wing. This drum I? in the present example, is mounted on and carried from the forward endof aileron hinge arm 3" by a bracket 18 that may be riveted or otherwise suitably secured to this hinge arm, that includes the depending spaced bracket arms J9 between which the cable drum I1 is rotatably mounted. A push pull rod 8!] is pivotally connected to the upper end of link M on the pivotal bearing-i6 and extends forwardly to and axially through the cable drum H and the bracket arm '59 of bracket i8. This push pull rod 89 is externally threaded at its forward end at 8! and. this threading engages suitable internal threading in an axial bore through drum. H, so that rotation of this drum through the engaged threading will force push-pull rod rearwardly or forwardly in accordance with the direction of rotation of the drum. An operating cable 82 is wound upon the cable drum l1 and extends through the wing to suitable pilotopera-ted mechanism. (not shown) for rotating the drum H in the desired direction to adjust the trim tab T through the medium of the mechanism hereinbefore described.

In the specific example of a trim tab as shown in Fig. 4 of the drawings, the cable drum H has been rotated in the proper direction to draw pushspull rod 89 forwardly and through link it and push-pull rod '15 to thereby lower and downwardly deflect tab T. In this instance, the tab has been deflected through an angle of approximately 15 relative to aileron A, the pivotal axis 16 of the adjusting mechanism then being moved from axial alignment with aileron balance axis 2 to a position spaced slightly forward of balance 2, as will be clear by reference to Fig. 4. When so adjusted, aileron A may be vertically raised about its remote hinge axis 8 and vertically deflected about its balance axis 2 in the control operation thereof without interference from or by the angularly-deflected trim tab T. The control operation of aileron A will not affect the adjusted position of tab T relative to the aileron except that due to the position of the pivotal bearing it at the upper end of link i l, spaced slightly forwardly of the balance axis 2 of the aileron, the tab 1* will be drawn or forced downwardly a relatively small distance through an other'degree or two of downward deflection when the aileron A attains the upwardly-deflected 

